JetBlue: All-You-Can-Jet $699
Sorry, this deal is expired.
Update: the passes are now sold out. JetBlue is running an All-You-Can-Jet promotion for $699. For one month you can fly an unlimited number of times with JetBlue seven days a week. There's also an option for unlimited flights for a month for 5 days a week (excluding Fridays and Sundays) for $499. Taxes and fees will still apply, but if you fly more than a couple times in a month this winds up being a deal. Flights must be used by 10/6.
Through 3/20, get spring break vacations with air and hotel from $159 at the Spring Fling Event at JetBlue Getaways (scroll to the bottom of the page to see details). It's valid on travel from 3/25-5/21 when you fly on Tuesdays and Wednesdays. Some restrictions apply.